The present invention relates generally to control systems for internal combustion engines, and more particularly, to an electronic throttle disable control test system.
Many previously known motor vehicle throttle controls have a direct physical linkage between an accelerator pedal and the throttle body so that the throttle plate is pulled open by the accelerator cable as the driver presses the pedal. The direct mechanical linkage includes biasing that defaults the linkage to a reduced operating position, also known as idle, in a manner consistent with regulations. Nevertheless, such mechanisms are often simple and unable to adapt fuel consumption efficiency, minimize regulated emissions, improve driveability to changing traveling conditions, and add significant weight and components to the motor vehicle.
An alternative control for improving throttle control and the efficient introduction of fuel air mixtures into the engine cylinders is presented by electronic throttle control. The electronic throttle control includes a throttle control unit that positions the throttle plate by an actuator controlled by a microprocessor using position feedback sensors. The micro controllers (or micro processors) are often included as part of a powertrain electronic control that can adjust the fuel and air intake and ignition in response to changing conditions of vehicle operation as well as operator control. Protection may be provided so that an electronic system does not misread or misdirect the control and so that unintended operation is avoided when portions of the electronic control suffer a failure.
One previously known type of protection to avoid unintended actuation of excessive throttle is to use a disable function of the electronic throttle drive electronics. The disable function allows the PCM to shut down the electronic throttle drive electronics in the event that the PCM senses a throttle position differing from expected throttle position. Unfortunately, typical electronic throttle systems do not test the integrity of the disable function.
The disadvantages associated with these conventional electronic throttle disable techniques have made it apparent that a new technique for testing the electronic throttle disable function is needed. The new technique should not intrude on normal throttle operation while verifying function integrity at least once each time the vehicle is powered up. The present invention is directed to these ends.
It is, therefore, an object of the invention to provide an improved and reliable electronic throttle disable control test system. Another object of the invention is to test the electronic throttle driver disable function. And additional object of the invention is to not intrude upon normal throttle operation.
In accordance with the objects of this invention, an electronic throttle disable control test system is provided. In one embodiment of the invention, a method for testing the integrity of an electronic throttle disable function begins by disabling the electronic throttle motor""s drive electronics (which is an integrated H-driver in the preferred embodiment). The H-driver is commanded to apply dull closing voltage, however, since the H-driver is disabled, no voltage is applied to the motor and the throttle remains at its default position. The throttle position voltage is then compared to a predetermined default position voltage. If there is a significant difference between the two voltages, then failure mode management is engaged. These voltages can be either xe2x80x9cabsolutexe2x80x9d meaning relative to system ground or xe2x80x9crelativexe2x80x9d meaning relative to the throttle position sensor voltage output at closed throttle, default position, or open stop position. This allows one to detect the voltage difference between default and closed stop.
At this point, we have verified that the throttle does not move when disabled. Then we have to verify that it does move when enabled.
The present invention thus achieves an improved electronic throttle disable control test system. The present invention is advantageous in that the integrity of the electronic throttle disable function is tested at least once each time the vehicle is powered up.